Study On Vacuum Frying Technology Of Instant Surimi Chips

Surimi products have always been favored by the public over the world.In addition to its delicious taste and delicate meat,its rich protein,minerals,vitamins and other nutrients are easily absorbed by the body,which is benefit for the body's health.At present,products made from surimi as raw materials include:fish balls,fish tofu,fish cakes,fish sausages,crab sticks and so on.Its products are mainly forzen and there are fewer recreational surimi products.The limit production type and weak processing technology of surimi product are the main problems that restrict the development of the surimi industry.The development of a new type of instant surimi chips is beneficial to the conversion and upgrading of the surimi industry,which will also provide new ideas for the development of surimi-based new products.Low-temperature vacuum frying technology was the technology of frying dehydration and drying of meterials under a certain degree of vacuum and low temperature.The use of low-temperature vacuum frying technology to produce instant surimi chips can avoid various adverse effects of oxygen and high temperatures on surimi,which,to the maximum extent,enables products to maintain their original color,aroma,taste and nutrient content.Therefore,the instant surimi chips were developed using low-temperature vacuum frying technology in this thesis.The optimized vacuum frying process of the instant surimi chips was investigated,and then the electronic nose combined with GC-MS was used to study their descaling process.Moreover,the changes of fat and water content in the instant surimi chips during the vacuum frying process were studied and the mass transfer kinetics were constructed.Finally,the stability and shelf life of the instant surimi chips was investigated.The main results are as follows:1.The optimized vacuum frying process of the instant surimi chips was investigated.The center combination was used for the experimental design.The fat content(R1),color difference(R2)and breaking force(R3)were used as product quality indicators.The optimized vacuum frying process parameters were as follows:vacuum frying temperature of 105 ?,frying time of 3min,chip thickness of 2mm.Under these conditions,the fat content,color difference and fracture force of the instant fish chips were 23.1334±0.79%,14.204±1.21 and 14.5277±2.16N,respectively,which were basically consistent with the theoretical predictions.2.The determination of fishy smell substances and the descaling process of instant surimi chips were studied.The electronic nose technology was used to identify the composition of the gas components of the surimi sample after adding pure milk,tea water,ginger powder and trehalose,and then the appropriate detergency agent was confirmed.On this basis,GC-MS was used to identify the gas composition of the surimi sample before and after deodorization treatment.The results showed that the optimized deodorization process was 3‰ of ginger powder and 7‰of trehalose without affecting the quality of instant surimi chips.Before deodorizing,the volatile materials were mainly n-hexanal,1,3-dimethylcyclopentane,and 2,3-octanedione,accounting for about 39.18%of the total.After deodorizing,the volatile substances were mainly furfural,heptaldehyde,(E,E)-2,4-decadienal,accounting for about 36.62%of the total.The major odor-producing substances such as n-hexanal decreased to 6.54%after deodorizing.The changes of fat and moisture in instant surimi chips during vacuum frying were studied.A dynamic model was used to simulate the changes in water and fat of instant surimi chips during vacuum frying.And then the classic mass transfer kinetics formula was used to verify the changes of the moisture content,frying temperature,and crisp thickness of the instant surimi chips during the frying process.The influence of the initial water content,the frying temperature and the thickness of the surimi chips on the water evaporation and the oil absorption were investigated.The resulting kinetic equation was as follows:The dynamical model for the water evaporation was:m-me =(m0-me)exp(-0.17963t)The dynamical model for the oil absorption was:F = Fe(1-exp(-9405.528t)4.The shelf-life of instant surimi chips was studied,and the preservation period of instant surimi chips was predicted using the acid value and peroxide value of oil as indicators.The acid value and peroxide value of instant surimi chips were studied in different packaging conditions and different storage time at different temperature of 5?,25? and 45?.Based on these results,a shelf-life prediction model of instant surimi chips was established using the acid value as an indicator:.Moreover,a shelf-life prediction model using the oxidation value as an indicator was established:.According to the verification test,the relative error between the value of the shelf life of vacuum fried surimi chips and the actual measured shelf life is within ± 5%,which indicated that both models can better predict the shelf life of vacuum fried instant suirmi chips at the temperature range of 5?40?.